docs: def validate_fluxtable(self):
          """Check for non-negative fluxes.
          If found, the negative flux values are set to zero, and
          a warning is printed to screen. This check is not done
          if flux unit is a magnitude because negative magnitude
          values are legal.
  
          """
          # neg. magnitudes are legal
          if ((not self.fluxunits.isMag) and (self._fluxtable.min() < 0)):
              idx = N.where(self._fluxtable < 0)
              self._fluxtable[idx] = 0.0
              print("Warning, %d of %d bins contained negative fluxes; they "
                    "have been set to zero." % (
                        len(idx[0]), len(self._fluxtable)))